Angiotensin converting enzyme (peptidyl dipeptide hydrolase, hereinafter referred to as ACE) occupies a central role in the physiology of hyptertension. The enzyme is capable of converting the decapeptide angiotensin I, having the sequence AspArgValTyrIleHisProPheHisLeu to an octapeptide, angiotensin II by removal of the carboxyterminal HisLeu. The symbols for various chemical entities are explained in the following table: